#include<bits/stdc++.h>
#define ll long long
using namespace std;
ll t,m;
ll timee[1005],v[1005];
ll dp[100000005];
int main(){
	cin>>t>>m;
	for(ll i=1;i<=m;i++){
		cin>>timee[i]>>v[i];
	}
	for(ll i=1;i<=m;i++){
		for(ll j=timee[i];j<=t;j++){
			dp[j]=max(dp[j],dp[j-timee[i]]+v[i]);
		}
	}
	cout<<dp[t];
	return 0;
}

蒟蒻求大佬调调代码